A unit of AT&T Inc. is helping certain customers collect a total of as much as $956.16 million in tax refunds as part of a settlement of a class-action lawsuit.

A federal judge in the U.S. District Court of Northern Illinois last week approved a settlement of the suit, which involved taxes being charged to customers who use AT&T (NYSE: T) phones to access Internet services.

Lawyers at a Midwestern law firm, Bartimus Frickleton Robertson & Gorny PC, filed lawsuits in all 50 states alleging that AT&T Mobility violated the Internet Tax Freedom Act, which places a moratorium on taxes on Internet access until Nov. 1, 2014.

The suits were consolidated into one case in Illinois last year.

"As part of the settlement, AT&T Mobility stopped charging certain taxes and fees on data plans," said Marty Richter, an AT&T spokesman, in an e-mail. "The settlement also requires us to help facilitate, on behalf of our customers, plaintiffs’ efforts to seek tax refunds from state and local taxing authorities on behalf of the Class. Any refunds will be passed along to (people) who are our customers, and initially paid the taxes".

AT&T Mobility did not do anything wrong, Richter said.

"AT&T Mobility collected only those taxes that we believed we were required to collect, and passed them along to state and local taxing authorities," he said. "While we strongly deny any wrongdoing, and no court has found that AT&T Mobility committed any wrongdoing, we agreed to settle these cases to avoid the burden and cost of further litigation.

Richter declined to reveal how much AT&T will spend on helping people collect their refunds.

Settling the distribution of tax refunds will be a particularly complicated and onerous process.

AT&T did not keep the excess taxes that were charged to consumers. That means — depending on state and local laws where excess taxes were collected — that AT&T has to collect tax refunds or it will receive a credit from a state or municipality and deposit the amount of the tax credit into an escrow account to be paid out later to consumers.

AT&T also had to calculate how much excess tax was collected from consumers because certain portions of a consumer’s bill were appropriately taxed and other portions were not.

For example, if a consumer’s monthly bill was $100 and $30 of it was for data plan services that allow access to the Internet, AT&T was supposed to collect taxes only on the remaining $70 and not assess taxes on the $30 Internet plan portion of the bill.